usually the detetectability is lowest directly in the middle of the metal detector spool. Therefore I would suggest, to place it as close to the middle as possible (during also using a product, as this is also heavily having influence on the result. if your cake is really flat, it should be placed more on the top (closer to center of metal detector). If your product is higher, it may perhaps been put into the product.

The recommendations are that the test piece should ideally be placed as close to the centre of the aperture as possible, This may is most likely to be in the product as the peroduct should be large enough to exceed the halfway line of the detector. if not if may be that the aperture is too big for the product. this means that the system has not been "optimised" and could result in a non-conformance or as has previously happened going to court and being fined.

It should be center of the apperature but most auditors like to see the test piece embedded in the bag as a piece of foreign material would be. Also taken in to consideration is the product size that you are putting through the apperature. Robert Rogers had a really good training on this for FSL 2013. If he doesn't care I will attach a few screen caps from his presentation, unless he wants to make it available himself.

What is the general consensus on the placing of test pieces when checking a metal detector

Hi Cakeman,

The BRC standard is quite clear, refer to 4.10.3.5:

'The test piece shall be passed as close as possible to the centre of the metal detector aperture and .............wherever possible be carried out by inserting the test piece within a clearly identified sample pack of the food'

It depends on the product size vs. the apeture size. The answer is actually "none of the above" because if the top of the product is the nearest place to the centre of the apeture, it should be there, if it's the centre of the product, it should be there.

Also don't forget the other axis; it should be leading edge, centre and trailing in convetional metal detection; leading and trailing for ferrous in foil.

Ideally the test pieces should passed through the detector in the centre of the aperture of the detection head and ideally embedded in a test pack. This provides the greatest challenge to the detection system. So if it detects the wands under these conditions and in consecutive pack format then you can be confident the system is optimised for the product and process rate.

I go with the centre of the aperture. We package dried fruit in 12-14kg cartons and tape the test piece to each end of the carton in line with the centre of the aperture. I have had auditors wanting us to place in the product but when you are talking a carton line and the carton is sealed it is impractical and I have successfully argued this point

I go with the centre of the aperture. We package dried fruit in 12-14kg cartons and tape the test piece to each end of the carton in line with the centre of the aperture. I have had auditors wanting us to place in the product but when you are talking a carton line and the carton is sealed it is impractical and I have successfully argued this point

Dear relsbels,

Out of curiosity, what is yr minimum (mm SS test piece) detection level at the centre of the aperture and within a 12-14 kg carton (assuming the 2 positions are not mutually exclusive). Sounds like a significant challenge. I once audited a flour production facility who had an end of the line MD check on something like 20kg sacks. They had no idea and were equally disinclined to want to know. NC No.X (n+1).

It depends on who you talk to. The manufacturer will tell you closest to the center of the aperture. Most customers want to see the package seeded with the test piece. Best practice is to place it in the package ensuring that the test piece is closets to the weakest point through the aperture, which is dead center.